1. Field of the Invention
This invention relates generally to windshield wiper drive systems and, more particularly, to that portion of such systems whereby wiper arms are parked below normal wipe patterns.
2. Description of Prior Art
In typical automotive windshield wiper systems of the type having a reciprocating drive link between a wiper arm and a motor driven crank arm, the wiper arm traverses a wipe pattern between fixed inner and outer limits as the crank arm rotates continuously in one direction. According to numerous prior proposals, the wiper arm may be pivoted through an extended arc to a parked position below the wipe pattern by increasing the length or throw of the crank arm during the final stroke of the wiper arm. In some prior proposals, the crank arm throw is increased by an eccentric member disposed between the crank arm and the drive link, the eccentric member being latched or otherwise held in one position for normal wipe operation and then released for pivotal movement to a position increasing the crank arm throw for parking the wiper arm. Proposals for latching and releasing the eccentric member have included detent arrangements on the crank arms sensitive to the direction of rotation of the crank arms whereby the eccentric member is unlatched when the direction of rotation of the crank arm reverses. In another proposal, the crank arm is supported for rotation in a slide member which is held by reaction forces in one operative position during normal wipe movement and then slides under the influence of opposite reaction forces to a second operative position more remote from the wiper arm when the direction of rotation of the crank arm is reversed. A variable throw crank arm assembly according to this invention has a fixed guide on the vehicle body engaging a guide follower rotatable with the crank arm whereby the throw of the crank arm is increased upon motor reversal and represents a novel alternative to heretofore known arrangements for effecting pivotal movement of wiper arms to parked positions.